Practice question

Mammalian hair follicle exemplifies stem-cell mediated regeneration where dedicated resident stem cells fuel cyclical turnover rather than forming blastema or using compensatory division of differentiated cells. Bulge region harbors slow-cycling multipotent stem cells activated by dermal papilla Wnt signals at anagen, producing transient amplifying progeny differentiating into hair lineage. Inhibitory BMP maintains quiescence during telogen. After wounding, bulge cells migrate to epidermis contributing to repair. This paradigm illustrates niche-regulated stem population sustaining tissue renewal, distinguishing stem-cell mediated regeneration from epimorphosis and morphallaxis and highlighting mammalian regenerative strategy for continuously renewing epithelia.